Parathyroid hormone regulates the concentration of the most potent vitamin D metabolite by increasing which of the following conversion?

Question

Quizplus · Accepted Answer

Parathyroid hormone increases the conversion of 25-hydroxycholecalciferol to 1,25-dihydroxycholecalciferol, the most active form of vitamin D, in the kidneys.  Parathyroid hormone (PTH) is synthesized and secreted by chief cells of the parathyroid glands in response to reductions in systemic Ca2+ levels. The release of PTH triggers an overall increase in serum calcium by both stimulating bone resorption and vitamin D-mediated uptake from the gut. The role of PTH in the hormonal function vitamin D is to enhance the expression of the enzyme responsible for the conversion of 25-hydroxycalciferol to calcitriol. This enzyme is 25-hydroxyvitamin D3 1-α-hydroxylase present in the proximal convoluted tubules of the kidneys and in bone.

Parathyroid Hormone Regulates the Concentration of the Most Potent Vitamin